You've 16127 MS - GUV Koodal Express @ 0515 from TCR to GUV.
Else, taxis should be available, just outside station.
Kerala SRTC bus station too is located very close to TCR railway station. Private buses to Guruvayur too are available from outside this bus station.
But don't think buses will be available at 0300; they might start service around 0600.